High frequency rotary welding transformer



Sept. 3, 1963 Filed Jan. 13, 1960 w. E. SHENK 3,102,943

HIGH FREQUENCY ROTARY WELDING TRANSFORMER 4 Sheets-Sheet 1 INVENTORWILLI AM E. SH ENK BY Y ' ATTORNEY W. E. SHENK HIGH FREQUENCY ROTARYWELDING TRANSFORMER Filed Jan. 13, 1960 Sept. 3, 1963 4 Sheets-Sheet 2INVENTOR EWILLIAM E SHENK i m WMM/@Aff N A ORNEY Sept. 3, 1963 w. E.sHENK 3,102,943

HIGH FREQUENCY ROTARY WELDING TRANSFORMER Filed Jan. 1s, 19Go y 4sheets-sheet s FIG. 8

FIG. 5

l FIG. 6

` I'NVENTOR WILLIAM E. sHENK IWW/ my? Arr RNEY Sept. 3, 1963 w. E. sHENK3,102,943

HIGH FREQUENCY ROTARY WELDING TRANSFORIVIER Filed Jan. 1s, 1960 4sheets-sheet 4 FIG.

FIG. IO

INVENTOR WILLIAM E. SHENK United States Patent O 3,102,943 HIGHFREQUENCY ROTARY WELDING TRANSFRMER William E. Shenk, Hubbard, Ohio,assignor to The Mc- Kay Machine Company, Youngstown, hio, a corporationof Ohio Filed Jan. 13, i960, Ser. No. 2,233

l2 Claims. (Cl. E19- 63) The present invention relates generally to thewelding art and more particularly to Welding apparatus of the type usedto heat and fuse an axially extending seam cleft in a cylindrical tubelength formed from metal strip in a continuous manner. The presentinvention seeks to provide a highly improved rotary transformer which,although not strictly limited thereto, is ideally adapted for weldingoperations wherein high frequency alternating currents are employed.

Welding transformers of the type having primaries and secondariesmounted for rotation with the secondaries being connected to rotatingwelding electrode wheels that engage the opposite edges of a cylindricaltube Length are well known in lthe -art as evidenced by my issued U.S.Patent No. 2,616,016, entitled Rotary Electric Resistance Welder, whichis assigned to the assignee of the present invention. 'Ihe use of highfrequency welding currents is also known in the art and, in accordancewith prior art practice, the high frequency currents are either inducedin the cylindrical tube length-or are transferred thereto by acombination of conduction and induction. As will be understood, highfrequency welding currents are widely employed in the fabrication oftubing from non-ferrous strip material, such as aluminum, for example,whi-ch is characterized by its low resistivity. While it has beenpreviously suggested to provide a rotary transformer for use with highfrequency alternating currents-as in the Caputo U.S. Patent No.2,265,627- such prior art ,apparatus is unacceptable for the purposesintended and is extremely limi-ted with respect to the range `offrequencies which may be employed.

It is therefore the primary or ultimate object of the present inventionto provide a rotary welding transformer which is ideally adapted for usewelding the opposite edges of a cylindrical tube length with highfrequency alternating current. The construction and utilization of therotary transformer is such that an almost unlimited range of frequenciesmay be employed. Upon proper engineering and design of a rotarytransformer constructed in accordance with the teachings of thisinvention apparatus can he provided which will operate in a highlyefficient manner at frequencies of millions of cycles per second.

Another object of the invention to provide a high frequency rotarywel-ding transformer which embodies improved means for transferring thehigh frequency alternaming electrical currents from the rotating currentcollector rings to the primary winding of the transformer. 'Ihe highfrequency currents which are at relatively large voltage potentialdiiferences are conducted from the current collector rings to theterminal connectors of the primary by means of concentric or co-axialconductors whereby the high potential fields normally surrounding theindividual and separated conductors of prior art apparatus areeliminated. Such high potential elds cannot ice 2 be tolerated `and areundesirable in the high frequency apparatus of the present `inventiondue to the substantial insulation and flash-over problems presented.

Still another object of the invention is to provide a high frequencyrotary Welding transformer that employs improved arrangements forcooling those parts which are subject to heavy current densities andthus generate substantial quantities of heat. As will be hereinaftermore fully apparent, cooling passageways and conduits are providedwhereby sufficient quantities of cooling iluid may Ibe circulated to allportions of the welding transformer-including the primary and secondary,the current collector rings, the supporting shaft, etc.

It is yet another object of the invention to provide rotary apparatus ofthe kind described which embodies improved means `for transferring thehigh frequency electrical currents from a stationary source thereof tothe rotating transformer with a minimum of potential loss. Relativelystationary current conductive brushes engage the opposite side faces ofthe current conductive collector rings in au improved manner and thesebrushes are cooled by circulating cool-ing huid therethrough.

Yet a further object of the invention is the provision in rotaryapparatus of the character described of an improved circuit arrangementoperative tc electrically interconnect the welding transformer with thewelding wheel electrodes. The disclosed arrangement is: such thatelectrical resistance and reactance losses are materially reduced andmaintained at a minimum but yet the assemhly is of relatively smallcross sectional area to facilitate the mounting thereof.

A further object of the invention is the provision of a high frequencyrotary welding transformer of improved mechanical structure whereby thedeilection and wear of the parts'is kept to a In this manner the rotarytransformer is adapted for sustained and continuous operations with a ofmaintenance.

The above, as well as other objects and advantages, will become moreapparent upon consideration of the following .specification andaccompanying drawing wherein there is disclosed a preferred illustratedembodiment 'of the invention.

In the drawing:

lFIGURE 1 is a fragmentary side sectional View depicting Ia weldingstation in a continuous tube fabricating line employing a high frequencyrotary welding transformer constructed in accordance with the teachingsof the present invention;

FIGURE 2, composed of FIGURES 2A and 2B, is a side view, partially insection, showing the high frequencies rotary welding transformer of thepresent invention;

FIGURES 3 and 4 are end sectional views taken along the section linesIII--III and lIV-AIV, respectively, of FIGURE 2A showing theconstruction of the elongated main supporting shaft;

FIGURES 5, 6 and 7 are end sectional views taken along the section linesV-V, VI--VI and VII-VII, respectively, of FIGURE 2A;

FIGURE 8 is an enlarged side sectional view showing the electricalconnections between the current rings and the terminals of the primaryWinding of the welding transformer;

FIGURE 9` is an end view of the primary winding and the core of theWelding transformer; f

FIGURE 10 is an enlarged sectional View taken along the section line X-Xof FIGURE 9; and

FIGURE 11 is an end sectional view taken along the section line XI-XIo-f FIGURE 2A.r

Referring novv to the drawing, and initially to FIGURE 1 thereof, thereis shown a high frequency rotary welding transformer, ygenerallydesignated by the reference numeral 10, which is supported by a suitablehousing 11. The high frequency rotary welding transformer comprises arear bearing portion 12, a transformer portion 13 and ya throat portion14 and the arrangement is such that large f high frequency electricalcurrents at relatively low potential differences and of oppositepolarity are conducted to a pair of large `welding electrode wheelsl 1Sand 16 which, of course, are insulated from each other.

The high frequency rotary welding transformer is encircled at the throatportion 14 by a yfront bearing. assembly 16 while the bearing portion 12of the transformer is encircled and rotatably supported by ahorizontally floating rear bearing assembly 17. The bearing assemblies16 and :1'7 are mounted from the housing 11 and are verticallyadjustable with respect thereto upon proper movement of the liftingscrews 18. The disclosed arrangement is such that the relatively heavyand large high frequency rotary welding transformer is rotatablysupported with the welding electrode wheels and 16 disposed inover-hanging relation with respect to a pair yof pressure applyingwelding rolls 19 and a cylindrical tube length, not shown, passingtherethrough. The welding electrode wheels 15 and 16 are adapted tocontact the opposite side edges lof a longitudinally extending seamcleft in the cylindrical tube length to heat and soften the same in acontinuous-manner. As the side edges of the seam cleft are heated andsoftened the pressure applying welding rolls 19 abut these edges underconsiderable pressure to complete the Weld therebetween.

Y 'lhe high frequency rotary welding transformer comprises an elongatedmain supporting shaft 22 of steel or other suitably rigid material whichcarries the principal elements of the apparatus. The shaft 22 ismachined to providean axial bore 23 that extends for a portion of thelength of the shaft 22. Received concentrically rWithin the axial bore23 is an elongated pipe 24 which projects rearwardly beyond the end ofthe supporting shaft 22. The axial bore 23 and the pipe 24 define a pairof concentric passageways for the flow of cooling lluid as willbephereinafter more fully explained.

A cup-like covercap 25 is bolted to the rear end of the shaft `22 andextends about the projecting rear end of the pipe 24. Journaled on theouter end of the cuplike cover cap 25 is a rotary lluid coupling 26which is adapted to be connected by an inlet conduit 27 and an outletconduit 28 to a suitable source of cooling fluid, not shown. The inletconduit 27 communicates with the passageway between the pipe 24 andaxial bore 23 in the supporting shaft through a suitable aperture 29provided in the side wall of the cup-like cover cap 25. The outletconduit 28 effectively communicates with the axial opening in the pipe24 as is clearly shown in the drawing.

rllhe supporting shaft 22 is radially bored at a point adjacent the rearend thereof to provide a plurality of radially extending passageways 30.The passageways 30, as will be later explained, provide a means forcirculating the cooling fluid through the current collector rings andthe y'windings of the transformer.

The forward end of the pipe 24 is threadably received in the supportingshaft 22 and isin communication with radially extending passageways 31in the shaft 22 which are disposed forwardly of the passageways 30. Thesupporting shaft is 0f increased diameter adjacent the radialpassageways 31 to define a pair of longitudinally spaced annular flanges32 and 33. Adjacent the forwardly disposed llange 33 the supportingshaft 22 is machined to 4, provide a plurality of longitudinallyextending and circumferentially spaced grooves 34 which form a portionof the cooling means for the high frequency rotary welding transformerof the present` invention. The grooves 34 communicate with alongitudinally extending offset passageway 35 in the forward end of thesupporting shaft 22 by means of a radial bore 36. The extreme forwardend of the supporting shaft 22 is also provided with a plurality oflongitudinally extending and circumferentially spaced groves 37. Thegrooves 37 extend rearwandly toward the yforward. end of the grooves 34but a portion 38 of the supporting shaft 22 separates these grooves fromeach other.

Mounted on the supporting shaft 22 between the rearwardly disposedshoulder 32 and a large locking nut 39 threadably received on thesupporting shaft adjacent the rear end thereof are a pair of elongatedtubular spacers 4l) and 41. The locking nut 39 is insulated from thespacer 41 and rigidly clamped between the spacers 40 and 41 is a currentcollector assembly generally desi nated by reference 42. The currentcollector assembly comprises a pair of current conductive collectorrings 43 and -44 which are axially aligned and separated from each otherby an annular insulating separator 4S. Each of the current conductivecollector rings 43 and 44 is mounted ron an annular mountingmember 46 asis clearly shown in the drawing. rlhe arrangement is such that themounting members 46, current collector rings 43 and 44 and theinsulating separator 45 provide a very com pact and rigid currentcollector assembly which is supported from and adapted to rotate withthe supporting shaft 22.

The insulating separator 45 is provided with four radially extending andnormally disposed passageways 49 and these passageways communicate withthe radial `passageways 30 in the supporting shaft 22. The outer ends ofthe passageways 49 are blocked and suitable lon gitudiually extendingthrough apertures 50 adjacent the outer ends of lthe passageways 49allow the fluid in the passageways 49 to spill into annular grooves 51ma-r chined in the adjacent faces of the current conductive collectorrings 43 and 44. The `grooves in the collector rings 43 and 44 aregenerally L-shaped in cross section and provide a means lfor coolingthese current collector rings.

The current collect-orring 44 is provided with a threaded bore 52 alonga major diameter thereof which communicates with the groove lltherein. Asecond threaded bore 53 in the current collector ring 44 alsocommunicates with the groove 51 therein and it will be noted that thislast mentioned threaded bore is disposed approximately one hundred andten degrees about the circumference of the current collector ring 44from the threaded bore 52. A threaded bore 54 is also provided in thecurrent co1- lector ring 43 and is disposed to one side of the verticaldiameter of this collector ring when the same is in the position shownin FIGURE 7 of the drawing. 'Ilhese threaded bores are employed toreceive current and/or cooling fluid conduits in a manner to behereinafter more fully explained.

The insulating separator 49 and the mounting members 46 are bored at 55as shown in FIGURE 7 to provide for the passage of a current and coolingfluid conduit. It will be noted that a plurality of annular O-ring typeof seals are provided between the insulating separator 45., the currentcollector rings 43 and 44 and the mounting members 46 to prevent leakageof the cooling lluid.

In the operation of the apparatus the high frequency alternatingcurrents are transferred to the current collector rings 43 and 44 by abrush assembly generally designated by the reference numeral 60. Thebrush assembly comprises a pair of longitudinally spaced arcuate sidemembers 61 which are rigidly attached to the opposite side faces 0f yanarcuate spacer 62. The side members 61 and the brush spacer 62 define agenerally U-shaped housing which nests with respect to a portion of thecurrent collector ring assembly 42.

Attached to the outer face of each of the arcuate side members 61`is adownwardly depending brush mounting bracket -63 which has a relativelylarge circular opening at the lower end thereof. Received within theopening of the brush mounting bracket 63- is a Igenerally tubular T-shaped brush holder 64 whose enlarged end is closed by a cover cap 65.Slidably received within the internal bore of the T-shaped brush holder64 is a cup-shaped brush `66 whose face is urged by fa compressionspring 67 into tight pressure engagement with the adjacent side face ofthe associated current collector ring. It is preferred that coolingmeans, including the conduits 68 and 69, be incorporated for circulatingcooling lluid within the tubular T-shaped brush holder 64 and thecup-shaped brush 66 to cool these members. The brush 66 is connected bysuitable leads, which may be the current conductive cooling fluidconduit 68, to one terminal of a high yfrequency alternating currentsource, not shown. The brush assembly comprises a pair of the cup-shapedbrushes 66 which each engage one of the current collector rings anditis, of course, necessary .to insulate the brushes 66 `from each other.To this end the brush spacer 62 and the side members 61 are formed frominsulating material while the brush mounting brackets `63, T-shapedbrush holders 64, cover caps 65, cup-shaped brushes 66 and springs 67are fabricated from highly current conductive material.

It will be noted that the current conductive brushes 66 engage the outerside edges of the current collector rings 43 and 44 rather than theperipheral and circumferential edges of these members as has beencustomary in the prior art. As will be understood, the skin effect isobserved at higher frequencies whereby the current is limited primarilyto the surface of the conductor. By employing the brush assembly 6()`and the current collector ring assembly 42 herein disclosed relativelylarge contact areas -are provided between the current conductive brushes66 and the current collector rings 43 and 44. Also, the high frequencyalternating current is transferred into the current collector rings insuch a manner that these alternating currents are dispersed across theentire outer radial surfaces thereof. The disclosed construction is suchthat resistance land reactance losses are maintained at an absoluteminimum when transferring high frequency alternating currents from asource thereof to the rotary welding transformer.

As intimated above each `of the cup-shaped brushes 66 is connected toone terminal of a source of high frequency alternating current. Varioushigh frequency generators are commercially available, such as rotatinggenerators, spark ga-p type generator and vacuum tube oscillators, forexample, and any type of generator which serves as a source of highfrequency, current for powering the welding transformer may lbeemployed.

Positioned on the supporting shaft 22 in concentric relation therewithis an elongated cup-shaped inner housing 72 which forms a portion of thesecondary circuit for the rotary high frequency welding transformer aswill be apparent. The cup-shaped inner housing 72 has an elongatedforward end portion 73 which is tightly received in concentric relationabout the forward end portion of the supporting shaft and cooperateswith the grooves 34 land 37 in this supporting shaft to dene a pluralityof longitudinally extending and circumferentially spaced fluidpassageways. The cup-shaped inner housing 72 also has an enlarged headportion 74 which encircles the enlarged portion of the supporting shaftin radially spaced relation with respect thereto. The spacing betweenthe supporting shaft 22 and the enlarged head portion 74 of thecupshaped inner housing 72 provides an elongated annular passageway 75which is in communication with the radial passageways 31 and thelongitudinally extending grooves 34 disposed about the circumference ofthe supporting shaft 22.

kA `second or outer cup-shaped housing 77 is positioned on the shaft 22in insulated relation with respect thereto andwith respect to the innerhousing 74. The outer housing 77 comprises an elongated forward endportion 78 and an enlarged head portion 79. The internal diameter of theelongated forward end portion 78` of the outer housing 77 isconsiderably larger than the outer diameter lof the elongated forwardend Iportion 73a` of the inner housing 72 to define an annularpassageway 80 extending longitudinally therebetween. The passageway 80is adapted to communicate with the grooves 37 formed in the forward endof the supporting shaft 22 by means of radial bores 81 in the forwardend portion of the inner housing 72. The outer periphery 'of -the headportion 74 of the inner housing 72 is positioned substantially radiallyinward of the inner wall of the enlarged head portion 79 of the outerhousing 77 to thus form an vannular enclosure 62 for the reception of aprimary winding 83 which is wrapped about an annular transformer core84. The transformer core 84 comprises an annular center ring 130` ofpowered and sintered magnetic material which is spaced from the turns ofthe primary winding 83 by inner and outer insulating ring spacers 131 asshown in FIGURES `9 and 1l of the drawing. The ring spacers 131 eachhave a plurality of longitudinally extending and circumferentiallyspaced grooves 132 on the surface thereof adjacent the annular centerring to define passageways for the ow of cooling lluid. The left hand oropen end of this annular enclosure 82 is sealed in a fluid tight mannerby means of an annular cover plate 85. Circumferentially spaced boltssecure the cover plate 85 to flanges 36 and 87 which extend outwardly ofthe outer housing 77 and inwardly of the inner housing 72 in the mannershown. The two housings 72 and 77 and the cover plate 815 form asecondary loop about the primary winding 83 of the high frequency rotarywelding transformer.

Included in the secondary circuit are, of course, the Welding electrodeWheels 15 and 16 which are electrically connected to the ends of thcouter housing 77 vand the inner housing 72, respectively, as will beexplained. The inner welding wheel electrode 15 is supported upon a ringmember 88 which is in rturn supported directly on the supporting shaft22 and axially engages a shoulder thereof. The ring member 88 is formedof highly conductive material and is preferably split to allow theaipplieation of suitable tangential pressure by bolts, not shown.

The outer welding electrode wheel 16 engages the rear surta'ce of asplit ring 90 which is supported on the forwlardly projecting end of theinner housing 72. It will be noted that the outer housing 77 terminatesat a point rearwardly of the inner housing 72. 'Illre currentco-nductive split ring 90 is .clamped to the inner housing 72 bysuitable bolts, not shown.

Retaining the current conductive split rings 88 and 90 y and the weldingelectrode wheels 15 `anrl 16 in axially aligned `and clamped relation'are la plurality of circumferentially spaced insulating bol-ts 91 whichextend axially through these members. Threadably received on the forwardrends of the insulating bolts 91 are clamping nuts 92 and the threadedrear ends of .the insulating bolts 91 are received in an annularclamping ring 93. Of course, suitable insulating rings and block-s, aswell as necessary fluid seals, not particularly shown, are provided.Tlhe .open `forward end of the inner housing 72 is closed by 'aT-slraped annular cover member 95 and a bolt and nuit assembly 96 whichis threadably received in the end of the supporting shaft 22. `Inessence, the above arrangement is such that the outer housing 77 is veryelficiently connected to the welding electrode wheel 15 while the innerhousing 72 is electrically connected to the ouiter Welding electrodewheel 16.

As shown in FIGURE 9 of the drawing, fthe primary winding 83 comprises aplurality orf individual thick c'opper conductors 97 which lare`connected in parallel and 7 which are wrapped in a single layer ofspaced turns 98 longitudinally about the annular transformer core 84. Inthe illustrated Aembodiment of the linvention three conductors 97 areshown as being connected in parallel to define the primary winding 03.The two outermost of the conductors 97 are insulated-#by Wrapping thesame in Teflon tape, for example-while the center conductor is lbare anduninsulated. The two 'ends of the pnim'ary winding 83 terminate in:terminal connectors 100 and, las

n will be observed in FIGURES l, 8 and 9 of the drawing, y

the terminal connectors ,are disposed in vertical planes laut are spacedlongitudinally with respect to each other .for reasons to tbe laterexplained. A ring of insulating material 101 i-s positioned between theannular cover plate 85 and the transformer core 84 to separate theterminal connectors 100 from cach other. A similar ring of insulatingmaterial `101i is positioned between the forward end of the transformercore 84 and the outer housing 77. It `will 'be noted that the primarywinding `03, transformer core 84 and thc insulating rings 101 and 103are of such a configuration Iand so mounted within the yannularenclosure 82 that the entire primary of the high frequency rotarywelding transformer may be immersed in cooling fluid.

At relatively low frequencies the tnansformer core 84 may lbe/fa'bricated from stampings of magnetic sheet material while atintermediate requcncies the transformer core may be formed frompowderedand sintered magnetic material Ias shown in the drawing. At relativelyhiglh frequencies the transformer core 84 may comprise a nonmagnetjicffonm upon which the primary winding S3 wrapped. It should be clearlyunderstood that the numlber of conductors comprising la turn, the sizeof the conductors, the number 'of turns, the spacing of the individualturns on the transformer core and the magnetic properties of .thetnansformer core are design factors which lwill be selected inaccordance with standard engineering principles -as fbest adapted forthe iirequency at which fthe rotary welding transformer is Ito openate.

It is, of course, necessary to provide current conducting means forinterconnecting the current collector rings 43 and 44 with the terminalconnectors 100 of the primary winding 83 and such means will now bedescribed. Threadably received the bore 53 the current collector ring 44is a current conductive pipe fitting 106 which receives one end of Iaproperly rbent current conductive conduit 107. The conduit 107 extendsforwardly and upwardly V'and terminates in la right tangled pipe fitting108. 'l'llre ,pipe iitting 10S is` received on the protruding rear end,of `a current conductive tubular conduit 109 whose flanged forward end110 is connected to one of the tenminal connectors 100 of the primarywinding 83.

Surrounding the cunrent conductive conduit 109 is am elongated tubularinsulator 111 that is preferably formed from Teflon or other suitableinsulating material. 'Ille tubular insulator 111 comprises-a forward endportion 112 which terminates adjacent `the flange 110 of the tubularconduit 109 Iand a rear end poi-.tion 113 which llas an increaseddiameter and is provided, Iadjiacent the rear 4end thereof, Ywith laplurality of integral longitudinally spaced land radially projectingheat radiating fins 114. Disposed in concentric relation about thetubular conduit 109 and the tubular insulator `111 is a sleeve 115 whichis formed of current conductive material. 'llhe tforward end of thecurrent conductive 4sleeve 115 is connected, by solderin for example, tothe other one of the terminal connectors 100 of the primary winding 83.The rear `end of the current conductive sleeve 115 terinitiates at 'apoint adjacent the forward one of the heat radiating tins 114 of thetubular insulator `111. IIt will be noted that the small diameteredforward end portion 112 of the tubular insulator 111 and the cunrentconductive sleeve 115 are so dimensioned thlat an annular passageway 117is provided. The current conductive sleeve 115 is also provided with athreadedbore 110 adjacent 8 the rear end thereof which' communicateswith the annular passageway 117. v y

Surrounding the cln'rent conductive sleeve 115 is a tubular memlber 119of insulating material. lit will be observed that lfthe currentconductive conduit 109v and the tubular insulator 112 extendthrough thecover plate 85, the vcenter of the rear lterminal connector 100` fandthe insulating ring 101 to the forward terminal :connector 100' 'of theprimary winding 83 'and that asuitable fluid seal is provided betweenthe tubular insulator 111 -and the tubular conduit 109 adjacent the rearIends thereof. The current conductive sleeve 115 and the tubularinsulating member 119 extend through la suitable aperture in the coverplate but .tenminate adjacent the rear terminal connector of the,primary windingl A83. The insulating ring 101 has suitable slotstherein, not particularly shown, which allow the rear terminal`connector 100 olf the transformer winding 83 to project therethrough. Afluid seal is provided Ibetween the current conductive sceve 115 and the,tubular insulator 111 to the rear olf the Iannular passageway 117 and aiurther fluid seal is provided between the cover plate `b5 and thetubular insulating memlbe-r 110.

Received within the threaded bore in the current conductive sleeve -saidbore actually Ibeing disposed at yan angle of ninety degrees from thelocation shown in FIGURE 8 of .the drawing-is ya tubular current con`ductive conduit 120 which extends Idownwardly and then longitudinally tothe rear through the opening 55 in the mounting members 46 and theinsulating separator 45. The tubular current conductive conduit 120 isthen conneoted by suitable current conductive pipe fittings 1211 intothe threaded bore 54 in the current collector ring 43. The abovedescribed yarrangement is such .that the current collector ring 43 is inelectrical contact with the rear terminal connector 100y while the othercurrent collector ring l44 is in electrical communication with theforward terminal connector 100. It Will be noted that the tubularconduit 109 and the current conductive sleeve 115 are disposed inconcentric relation whereby `the magnetic elds surrounding theseconductors are eliminated. This arrangement substantially mitigatesserious flash-over and high voltage insulation problems while yet thelassembly is extremely small and compact.

As will be more fully apparent, cooling lluid is supplied Ito ftheannular enclosure 82 through the various conduits land passagewaysprovided in themeans for transferring the high frequency currents irom'the current collector rings to the tnansformer primary winding. TheVsupply of cooling iluid to the annular enclosure 82 1s augmented by aflexible and insulating conduit 123 extends from the threaded .bore 52in Ithe current collector ring 44 to the annular enclosure 82 as isshown in FIG- URE 2 of the drawing.

In the use of the apparatus ing electrode wheel-s 15 and edges o f 'acylindrical tube length while high frequency `alternating currents at arelatively high voltage are supplied to the cup-shaped brushes 66 bymeans of the current conductive conduits `68. The brushes 66 transferthe high frequency currents to [the current collector rings 43 `and 44in a continuous manner :as -the transformer is rotated about its axis.The brush lassembly is operative to effect this 'transfer with 'aminimum of reactance and res1stance loss. l

The :current collector ring 44 is connected to the forward terminalconnector 100 of the primary winding 83 by the pipe fitting 106, conduit107, fitting 108 and the tubular conduit 109 While the current collectorring 43 is connected to the rear terminal connector 100 by the pipettings 1,211, conduit 120 and the current conductive sleeve 115. Asmentioned above, the disclosed means of interconnecting the terminalconnectors 100 of the primary winding S3 and current collector rings ishighly advantageous since the same is quite compact and since abovedescribed, the weld-V 16 engage the opposite side 9 insulationand-ash-'over problems are minimized. transfer hfv :high frequencyelectrical currents also takes place with afminimu'm off resistance andreactance drop.

The high .frequency alternating currents in the primary winding l83induce a'relat-ively low voltage and high amperage welding current'atthe desired frequency in the secondary loop. Thisv secondary 'n loopcomprises the cover plate 85, inner housing *'72,y louter housing 77,the welding wheel electrodes 15 Iand 16 and the cylindrical tubelength., It will be' noted that` the inner and :outer liculsifngs. are-concent-ric'ally mounted throughout their lengths and this `isparticularly important in providing a ,relatively small andcompactvrotary welding trans for-nier -forense =of mounting and` usewhile yet high voltage insulation problems lare substantiallyeliminated. The enti-re secondary loop is characterized by its extremesimplicity and compactness. y

Cooling fluid is, of' course, lcirculated thro-ugh the high.,`:frequencyyrota-ry welding transformer and this is accomplished byintroducing` iluid under pressure into ,theannular passageway defined bythe axial bore 23 in the elongated sha-ft Z2 and the pipe 2.4 throughthe inlet annularenclosure 82 defined by they inner and outer," vhousingmembers.; The cooling iiuid in the annular 'groove-'Slot vthe currentcollectorring 44 also is intro;-

duced into the/annular enclosure 82.by means of the tubular conduits 107and` 109 `and by the llexibleconf duit 123. llt will 'be noted that theinterior of the 4.tulmlar conduit 109 and the current conductiveringmemberl 1,15

lare in intimate contact with the cooling fluid whereby the j same arein highly eicient heat transferrelation/therelwith.' The Lcooling uidi'lows about 'the transformer core and through 4v'the grooves 132 |inthe insulating ring spacersn131'fto very effectively cool the .annularof magnetic material 13G. The arrangement is such that theannular-.ringwof magnetic ymaterial 130 4is sulrrounded by coolingfluid.

From the lforward 'end of the Yannular Ienclosure 82 the coolinguidltravels along the passageway t), down through the radialpassagew-ay81' -in the forward-end portion of the inner 'housing 72, along thepassagewaysr defined by the longitudinally extending and circumferen-This` thatmany changes may be made in the illustrated embodiment of theinvention without departing from the clear teachings thereof.Accordingly, reference should be had ltoythe following appended claimsin determining the true scope and intent of the invention.

I claim: t

l. Ahigh frequency rotary welding transformer for tube mills and thelike comprising a shaft having a pair of current-conductive .sleevesthereon insulated from each other except at one end thereof to form asecondary loop, at least the outery sleeve adjacent said end beingenlarged to form an annular space for the reception of an annular4transformer core having a primary winding rings mounted on said shaftoutwardly lofbut adjacent to the first mentioned end of said sleeves andelectrically connected throughcurrent and `uid conductive conduits withthe two end terminals of said primary winding, said rings being yhollowwhereby fluid supplied'thereto may enter lsaid conduits, and passagemeans in said shaft to supply cooling fluid to said collector rings.

2; An assembly according to claim l further characterizedzin that saidconduits are openly connected with said annular space whereby coolinguidhowing through said conduits from said collector ringsmay .be dischargedinto said annular space and further including a fluid outlet for saidannular space comprising passage means extending between said sleevesoutwardlyv towardwsaid wheels, and other passage means includingopenings in said 'shaft to conduct coolingl fluid :from` adjacent` said,Welding wheels axially Welding electrode wheels mounted atv oneend ofksaid tiallyf spaced grooves 37 in the supporting `shaft 22a'b'out the4forward 'endof Ithe supporting shaft, into the longitudinally extendinglbore 35, outwardly through the radial ypassageways 36,` along 4thecircumferentiallycspaced l Iand longitudinally extending .grooves 34 inrthe supporting' shaft, down through the radial passageways 3l, throughthe pipe 24 and thence to the source 'through theoutlet 1 conduit28wof-the rotary fluid coupling, lt will be'noted that the concentricinner and outer housing of the eee- -ondary loop are also ysurrounded byconcentric layers'of cooling '.fluid lwhereby a highly :eicient heattransfer' meansis provided. The various coolingpassageways` in thehighfrequ'ency rot-ary welding transformer lor the present invention areso, disposed and of .such a sizethat overheating Iof the, transformer atany localized area .is precluded even ,when the transformer soperated.oontinuouslyyor sustained periods. Of course, cooling fluid is alsosupplied :to the brushes 65 lof -the'brush assembly by means oftheconduits 68 :and 69 during the fopen, anon of thel high frequency notarywelding transformer..

It should thus `be -apparentthat I` have accomplished vthe objectsinitially set. forthy by providing a'higbly im- .proved and extremelysimplilied rotary' weldingtransformer which is` ideally adapted r'forusewith high fre `quency alternating currents. Itfshould be understoodback through said assembly beyond said collector rings.

its center portion a transformer having a primary winding and asecondary loop which lis connected to a pair of shaft, a pair of hollowcurrent collector rings mounted on said shaft at the axial end vofsaid'transformeroppositesaid Wheels, means including passageways in saidshaft to supply cooling fluid to said rings, vand means `comprisingcurrent and `fluid conductive conduits y'interconnecting said rings withthe terminals of the primary winding ifor use with :high frequencyalternatingcurrents in the Welding of `the adjacent side edges of a tubelengthwhich comprises an elongated and centrally disposed mainsupporting shaft, apair of welding electrode wheelspmounted adjacent oneendof said supporting shaft, said welding electrode wheels. beingdisposed in radial planes and being axially insulated from eachL otherpa primary winding, said primary winding being mounted from said `sup-yportingshaft intermediate the ends thereof,.a secondary loop`interconnecting said welding electrode ywheels and said primarywinding, said secondary loop comprising an inner elongated cylindricalyhousing mounted concentricallly on said supporting shaiit between saidprimary winding and said welding electrode wheels, an. outer elongatedcylindrical housing, said outer housing having a largerY diameterfthansaid inner housing and being mountedv concentrically about said mainsupporting shaft and said innerhousing in insulated relation withrespect to said inner housing between" said prim-ary winding and saidwelding electrode wheels, said inner andyouter housings being currentconductive to deiine concentric conductors,

i iih l y means to circulate cooling tluid about said inner and outerhousings,-said means to circulate comprising a plurality oflongitudinally extending and circumferentially yspaced grooves in theperiphery of said supporting shaft,

a secondary -loop interconnecting said primary winding and said weldingelectrode wheels, saidvsecondary loop comprising an `inner Ycylindricalhousing mounted con-t centrically on said supponting shaft, an outercylindrical housing mounted concentrically about said supporting shaftand said inner housing and being insulated from said inner housing,`said inner and outer housings being v current' conductive to denneconcentrici conductors,

means to circulate cooling iluid about said inner and said outerhousings, said means to circulate comprising a iirst set oflongitudinally extending and circumferentially i spaced passagewaysdisposed between said supporting ,shaftand said inner housing, a secondset of longitudinally extending 'and circumferentially spaced passage-Ways disposed between said inner and said outer housings, meansinterconnecting said passageways, said means interconnecting saidpassageways comprising a third set arcanes .of longitudinally extending`and circumferentially spaced passageways disposed. between saidsupporting shaft and said inner housing and longitudinally of said firstset of passageways, a radial bore in said innerv housingjinter-` vconnecting said second and saidthird set 'of passageways,

a longitudinally extending bore in said supporting shaft,

and a radial bore in said supporting shaft interconnectingsaid'longitudinally extending and said tirst set of passageways,V '7. Arotary welding vtransformer of the type adapted for use with highfrequency alternating currents in the comprises anv elongated 4andcentrally disposed main supporting shaft, `a'pair ofWeldingelectrode'wheels mounted on said shaft, a primary winding mountedonv said shaft,

a secondary loop interconnecting said primary winding `lwelding of theadjacent side edges of a tube length which and said'welding electrodewheels, said secondarygloop comprising aninner cylindrical housingmounted concentrically `on said supporting shaft, anouter cylindricalhousing mounted concentrical-ly about' said supporting shaft and said`inner housing and beingV insulated from said inner housing, said innerhousing and outer housner' and 4said outer housings, meansinterconnecting'said passagewfays',said iirst set of passageways beingdelined by a plurality ofrlongitudinally extending and circum-vferentially spaced grooves formed in saidfsupporting shaft; f

f y8. A rotary welding transformer ofthe type. adapted for usefwith highfrequencyl alternating currents in the. welding of the adjacent sideedgesof a tube length which comprises an elongated main supportingshaft, a pair of welding .electrode wheels mounted on said supportingshaft, a primary winding having a pair of terminal. con-' nectorsmounted on said supporting shaft, a secondary loop interconnecting saidprimary'winding and said welding electrode wheels, meansto transferalternating currents from a' source thereof to -said terminal connectorsof' said primary winding,` said last mentioned means comings beingcurrent conductive to deiine concentricrconductors, means tocirculatelcooling fluid about .said in- ,nerfandsaid outer housings,said means to circulate comf ,prising a first set of longitudinallyextending and circumferentially spaced passageways disposed between saidinprising a pair of current collector rings, an insulating spacer, saidlcurrent collector vrings and saidr insulating spacer being mounted onsaid supportingsh-aft .inV aligned relation with said insulating spacerbeing'ldisposed between said current collector yrings, means connectingeach of said current collector rings iwith one 'of said terminalconnectors, means to circuflate: coo-ling iluid through saidcurrentcollector rings fand said sulating spacer, said lastmen'tioned meanscomprising,

an axial bore in said supportingr shaft, a plurality of radialpassageways in said insulating spacer, radial passageways in saidsupporting shaftinter'connecting said radial Spassageways 'in saidinsulating spacer and said. axial-,. ibore in said supportingshadinannular grooves in thev adjacent radial faces of said currentcollector rings, and passage- YWays interconnecting said radial bores insaidmsulating spacer and said annularl grooves in said current collectorrings. f

9,. A rotary weldingtrans-former of the type-adapted for use with highfrequency. alternating currents in the" welding of the adjacent vedgesof a tube length which comprises a primary winding having a pair ofvconcentric vbut spaced terminal connectors, asecondaryloop, mear'ls'totransfer alternating currents from a source thereof` to" vsaidterminalconnections of said primary winding, said means to transfercomprising a pair of insulatedfconcen-E tric conductors, said pair'ofinsulated concentric conductors comprising a tubular conduit of currentconductlve material passing vthrouglione of `said connectors andlelectrically'connected to the other ofsa'id connectors, ,a tubularinsulator ,mounted in ,conce'ntric relation-lon .said

tubular conduit,1a current conductive annular.mem-ber.'v mounted inconcentric relation about said ltubular con- -duit and said tubularinsulator andconnected to said other terminal connector; and aninsulating sleeyeif surrounding said current conductive annular memberin concentric relation with respect to saidv tubular cond/1th f saidtubular insulator, and said nular member. y l Y l '10. Apparatusaccording to claim l9furthercharacterized Vin that said primary Windingis. mounted in an -annular enclosure having a back cover plate, a ring of insulating material disposed between said primary wii:ldv

ing and said back cover plate, said terminal connectprs of said primaryWinding being disposed in ver-ticalgbut longitudinal spaced planes, oneof said terminal con-V nectors beingrpositioned between said back coverplate and said ring of insulating material, fthecther or said?` terminalconnectors being positioned between. said primary Winding and said ringof insulating material, said tubular conduit and said tubular insulatorextending throughisaid back cover plate and saidl ringfof`insulating-material, said tubular conduit being connected to said otherlterminal connector, said current conductive annular member and saidinsulating vsleeve extending through said back cover plate, and saidcurrentconductive annular member being connected to saidV fone;Aterminal connector. i

ll.. A high frequency rotary Welding transformer for tube mills and thelike comprising an annular currentv vconductive casing having inner andouter-*concentric* walls interconnected at one end to deiine asecondary" current loop and an annular space forreceptionlof a core andprimary structure, said core comprising an arl-,

nulus of magnetic material, and a layer of a heavy current conductorwound spirally on said annulus, a hollow` co-axial current-conductivekconnector extending outwardly of, said annular space and` connected atits inner end to the end terminals of said conductor forming the primarywinding, means to connect highv frequency al-- ternating current to theco-axial conductors of said con- 1 cooling uid through said nector, andmeans to circulate connector. 1

12. i'pparatusiyfor supplyingfhigh frequency resistanc Welding currentin the manufactureof metal ttubes=chariy acterized in that atransformerhaving vannular nested:` primary and secondary circuits is carried on arotatable current conductive an;

former While a pair of adjacent parallel insulated Wheel electrodes arealso mounted on said shaft at the oppo y site end of said transformerandr yelectrically connected to the second-ary circuit thereof,'co-axial tubular members connected to -the terminals of I'the primarycircuit lof said transformer and extending outwardly of said one end ofsaid transformer and electrically connected to said v rings wherebyelectrical energy of lh-ighfrequency is supplied to said primarycircuit, said rings being yhollow-and being supplied by coolingfluid bypassage means in said shaft, aud the means electrically connecting saidrings to said co-axial tubular members being hollow'to permit v lll theilow of cooling fluid from said rings through said coaxial members andinto Ithe space surrounding said prif vmary circuit.

References Cited in the file of this patent UNITED STATES PATENTS:1,394,901 Hobarrj oct. 25V, 192,1 11,469,720v Dorsey 7 Oct. 2, 19232,265,627 Caputo Dec. 9, 1941 2,561,739 Hunter July 24, 1951 2,666,121Allardt Ian. 12, 1954 2,790,100 Caputoet al. Apr. 23, 1957 2,964,611()1960 y Macley Dec. 13,

1. A HIGH FREQUENCY ROTARY WELDING TRANSFORMER FOR TUBE MILLS AND THELIKE COMPRISING A SHAFT HAVING A PAIR OF CURRENT-CONDUCTIVE SLEEVESTHEREON INSULATED FROM EACH OTHER EXCEPT AT ONE END THEREOF TO FORM ASECONDARY LOOP, AT LEAST THE OUTER SLEEVE ADJACENT SAID END BEINGENLARGED TO FORM AN ANNULAR SPACE FOR THE RECEPTION OF AN ANNULARTRANSFORMER CORE HAVING A PRIMARY WINDING THEREON, WELDING ELECTRODEWHEELS MOUNTED ON THE OTHER ENDS OF SAID SLEEVES, A PAIR OF INSULATEDCURRENT-COLLECTOR RINGS MOUNTED ON SAID SHAFT OUTWARDLY OF BUT ADJACENTTO THE FIRST MENTIONED END OF SAID SLEEVES AND ELECTRICALLY CONNECTEDTHROUGH CURRENT AND FLUID CONDUCTIVE CONDUITS WITH THE TWO END TERMINALSOF SAID PRIMARY WINDING, SAID RINGS BEING HOLLOW WHEREBY FLUID SUPPLIEDTHERETO MAY ENTER SAID CONDUITS, AND PASSAGE MEANS IN SAID SHAFT TOSUPPLY COOLING FLUID TO SAID COLLECTOR RINGS.